In the processing of a biological fluid, such as blood or a blood component, the ability to draw a sample at a selected stage in the processing often provides useful information. For example, obtaining a sample may provide an indication of the composition, concentration or other property of the fluid being processed. Sampling may also provide information about the biological fluid at a selected stage of the processing which may, in turn, dictate future steps in the processing. For at least these reasons, it would be desirable to obtain a sample that is truly representative of the fluid being processed.
Sampling containers are commonly used in biological fluid processing, such as in the collection, manipulation and/or separation of biological fluid. In one non-limiting example, the biological fluid may be a blood product such as whole blood or a component thereof. Where a disposable fluid processing kit is used, a sample “pouch” may be incorporated in the fluid circuit of the kit. Such sampling pouches are often made from two flat sheets of a biocompatible polymeric material wherein the sheets are sealed together along their respective peripheries. The pouch defines an expandable interior chamber which holds the desired fluid and from which samples can be withdrawn. A potential drawback of such flat sheet containers is that they may include corners and/or spaces where fluid may be trapped or otherwise retained. In addition, such containers may have excess surface area where fluid may be trapped, requiring additional manipulation of the container and/or multiple reconnections to obtain additional measurements. Fluid or cellular material trapped in the corners may affect the homogeneity of the fluid to be sampled. This may potentially lead to errors in the measured concentration or composition of the biological fluid, thereby skewing the sample results.
In U.S. Pat. No. 7,699,828, the entire contents of which is hereby incorporated by reference, the interior chamber of the sample pouch has a generally circular profile. The circular profile eliminates corners and the dead spaces where fluid or cellular material may be retained. Fluid containers of the type described in the above-referenced U.S. Pat. No. 7,699,828 are likewise made of flat sheets that are sealed together along their respective peripheries. While such containers are an improvement over sample pouches with less circular interior chamber profiles, they may still allow for cellular material or fluid to become trapped between the sheets of the pouch.
In addition to ability to obtain a representative and homogenous sample, the processing of a biological fluid may, at times, also require the delivery or addition of therapeutic or other agents to the biological fluid. Often, the delivery of the agent is done by injection of the agent into a container interior through a port adapted to receive the injecting syringe. The agent is often required to be mixed with the biological fluid to provide a homogeneous composition. Flat pouches of the type described above, while allowing for mixing, also pose the potential problem of cells being trapped in spaces between the sheets of the container, resulting in less than ideal mixing of the agent and the biological fluid. Additionally, use of such pouches may (where multiple sampling is desired) require several sequential attachments of such containers which may, under certain circumstances, jeopardize the sterility of the processing system. Thus, it would be desirable to provide a biomedical container that eliminates these potential dead zones that may trap cellular material, particularly during the accessing of the container contents to either (a) draw a sample, and/or (b) deliver an agent. In either aspect of biological fluid processing, a higher degree of confidence in the homogeneity of the biological fluid within the biomedical container is desired. It would also be desirable to provide a biomedical container that allows for sampling at various stages of a fluid processing procedure without the need for multiple container connections and disconnections.